how can an hard drive from 2003 be still under warranty these days?
WD automatically starts counting the warranty from the date of manufacture.
But you can provide purchase information to WD and have the warranty dates amended.
Back then the Caviars had a one year warranty, not three.
The OP did say that the drive was just purchased (one must assume from really old stock, if that “2003” wasn’t a typo).
With proper purchase information submitted to WD, as long as this was an original retail sale, and not a re-sale, then the warranty won’t expire until a year from now, regardless of manufacture date.
If your registered drive still show an incorrect warranty date, please send us an email and attach a copy of your proof of purchase. We need your proof of purchase in order to update the warranty to start from the date of purchase."